Process of treating steel



NORMAN C. EINWECHTER, OF PHILADELPHIA, PENNSYLVANIA.

PROCESS OF TREATING STEEL.

No Drawing.

To ail whom it may concern:

Be it known that I, NORMAN C. EiNwnoi-I- 'rnn a citizen of the UnitedStates, residing in 1 hiladelphia, Pennsylvania, have invented Processesof Treating Steel, of which the following is a specification.

In the use of rivet sets, drills, cutting chisels and the like such asare employed in pneumatic tools, I have noted that these usually failedby reason of the crystallization occurring in their structure due to thepeculiar and oft repeated stresses to which they were subjected. Thiswas noticeable not only in alloy steels, where, in the case of rivetsets for example, it was found that these would invariably fail beforemore than five hundred rivets had been headed, but also, andparticularly, in the case of ordinary carbon steels.

One object of my invention therefore isto provide a method or processfor so treating .alloy steels and more particularly vanadium steel, asto materially increase the useful life of tools of the above class madetherefrom. In carrying out this invention I so operate on the steel asto render its structure substantially homogeneous throughout andparticularly to prevent the existence in the body of a tool made fromit, of stresses such as would be due to irregular or uneven heattreatment.

According to my invention, in a typical case I preheat a tool of alloysteel evenly and slowly to 1250 F, moving it about on the floor of thefurnace during such operation so as to insure that its entire mass isbrought to the desired temperature. An alloy steel which I have employedin carrying out my invention would have a composition as follows:Vanadium about 0.20 of 1%, carbon .60 to .80 of 1'71, and manganeseabout 0.25 of 1%. 'hen this condition exists, it is transferred to asecond furnace, where it is heated to a temperature of from 14.30 to1440 hi, c. from thirty to forty dcarecs above 1400 which the cri icaltemperature of the steel under co. the critical temperature being thatto which it should be brought in order that it may thereafter beproperly harden. l. steel reaches this temperature its criticaltemperature and or. uniform distribution of heat its entire mass, it isquenched i in; a temperature of about i is allowed to remain until ithas Specification of Letters Patent.

Patented Nov. 1.6, 1920.

Application filed May 5, 1919. Serial Nd, 294,662.

appreciably vibrate, when it is at once removed to an oil bath andsubjected to an appropriate tempering treatment forming no part of myinvention.

In explanation of the above process I would point out that for theparticular steel above referred to, 1400 I. has been found to be thecritical temperature to which it should be heated in order that it .maythereafter be suitably hardened, and

my invention resides in the discovery that by raising its temperaturefrom 30 to 40 above this critical point prior to the quench ingoperation, the innermost portions of the body of said steel as well asits outer parts, will have the critical temperature of 14:00 when thequenching actually takes place. Under these conditions the whole mass ofsteel is free from injurious stresses.

If on the other hand, the body of steel is heated to 14:00 as has beencustomary, and is then-quenched, its outer portions will unavoidablycool in the interval between its removal from the furnace and its entryinto the Water, so that the parts of its body immediately adjacent itssurface have a temperature below H00 while its interior is stillapproximately at 14.00 withthe result that those stresses are set upwhich I have found cause the rapid failure of the finished tools, whenused in pneumatic apparatus prior to my invention. \Vhere rivet sets asordinarily treated would invariably fail before more than five hundredrivets had been headed, I find that when subjected to my treatment theywill almost without exception head from twenty-' to twenty-fivethousand'rivets, and in extreme cases, as many as one hundred andtwenty-five thousand rivets have been headed before failure of the toolhas occurred. the results attained being dependent upon the expertnessof the operator in treating the tool according to my invention.

It will be understood that while in the above description I havereferred particularly to rivet sets as benefiting by my invention, thelatter is equally and advantageously applicable to all tools subjectedto vibratory or rapidly alternating stresses such as exist in pneumatictools under conditions of use and which have been found in the past tocause rapid crystallization of the structure of the tools employed.

It is further to be noted that while I have referred to l4 30 l0 F. asthe temperature yent-ion, the essence of which consists in heating thebody'of steel under treatment from twenty to forty degrees above itssocalled critical point as above defined which point would vary with thecomposition of the particular steel under treatment.

I claim:

1.. The method of treating vanadium steel which consists in heating itslowly to a temperature of from 1430 to 1440 F." quenching it in waterat a temperature 0 60 F. until vibration ceases; and then placing it inan oil bath. T

2. The method of treating vanadium steel which consists in slowlyheating it to 1250 F. in one furnace; transferring it to a secondfurnace and heating it therein to a temperature of from 1-130 to 14:40E; quenching said steel in water until vibratlon has ceased; andthereafter transferring it to an oil bath.

3. The method oftreating a tool of vanadium steel which consists inheating it evenly and slowly to a temperature of about 1250 F.;thereafter increasing its temperature to ll-1440 F.; and quenching itwhen its entire mass has a temperature of about 1400 F.

In witness whereof I aflix my signature.

NORMAN C. 'EINVVEGHTE-R.

